1. Field of the Invention
The present invention relates generally to data storing technology and, more particularly, to selective data storing technology.
2. Description of the Related Art
With the development of technology, the costs required to store large amounts of data have gradually decreased, while, with the advent of the multimedia era, the amounts of data that users desire to store have increasingly grown. Accordingly, there is still needed for technology for capacity-efficiently storing data in a mass storage device.
In general, mass storage devices may be classified into rotating disk-based hard disk devices and nonvolatile memory device-based flash memory devices.
Although hard disk devices have high storage density per unit area, can be fabricated to have huge capacity to terabyte and can be manufactured at low cost, they have relatively low speed, and are vulnerable to impact because they are dependent on mechanical parts. Hard disk devices include various groups of commercial products ranging from a group of expensive products capable of ensuring high performance and high reliability to a group of inexpensive, low-performance products, and thus various level products are being supplied to the markets.
In contrast, although until now flash memory devices have rather low storage density, cannot be fabricated to have high capacity and are manufactured at high cost, they are robust to impact because they are based on semiconductor chips and printed circuit boards. Flash memory devices also include a group of expensive, high-performance single-level cell (SLC) products and a group of multi-level cell (MLC) products, and thus consumers can purchase various level products in terms of performance, capacity and lifespan.
Accordingly, some mass storage device products are configured in a fashion of attaching high-speed, high-performance, high-reliability flash memory to low-speed, low-performance hard disk storage, as a cache, thereby enhancing the performance of a hard disk device.
Furthermore, a plurality of mass storage devices can be combined and then driven as a super-high capacity storage system. In such cases, the individual mass storage devices may frequently have different speeds and different performances. Although a super-high capacity storage system had been at first constructed using the identical kind of mass storage devices, replacing old parts with new ones over time results in mixed products with different speeds, different performances and different capacities in the single system.
In the above-described storage environment in which mass storage devices having different speeds, different performances and different capacities are intentionally or naturally present together, a technology for, first, selecting a mass storage device where data will be stored from among the mass storage devices based on the characteristics of the data to be stored, and then storing the data, is required to achieve optimum storage performance.
For example, a method may be used that, based on the file extension, type or attribute, amount or access frequency of data to be stored, or a combination thereof, stores a system file, an executable file, a frequently accessed file, and a temporary file in a flash memory device and stores a large multimedia file in a low-speed hard disk device.